Thermo-compression bonding is a process of attaching an electronic component, such as an integrated circuit die, to a substrate. This is accomplished by bonding solder bumps on the component to bond pads on the substrate using a combination of heat and pressure. The resultant solder bump interconnection is effective to convey electrical signals between the component and the substrate.
In thermo-compression bonding, a substrate must be transported and heated such that the substrate is held in place and such that the thermal expansion of a frame, which can have a different coefficient of expansion than the substrate, does not effect the location or surface flatness of the substrate. The bumped surface of the substrate must be substantially parallel to the die for a successful thermo-compression bond. Therefore, it is crucial for the substrate to be flat and to remain flush with the heated platform during processing.
Current technology nests a substrate in a pallet, known as a carbon boat, and requires the carbon boat to be elevated to a proper temperature to conductively heat the substrate to a temperature sufficient to allow thermo-compression bonding. However, due to imperfections in the carbon boats, the surface flatness cannot be reliably assured and the die and the surface of the substrate cannot be guaranteed to be parallel to a degree necessary to assure effective thermo-compression.
Prior art workstations mechanically grip the substrate and move it to a carbon boat. Flexible membranes, composed of thin polymeric film, are used as substrates. Because of the fragile nature of flexible membranes, prior art mechanical workstations cannot effectively process flexible membranes due to the inability of current mechanical grippers to secure flexible membranes without damaging them.
Therefore, a need exists for a workstation that is capable of thermo-compressing dies onto a flexible membrane without manually or robotically gripping the flexible membrane.